troubles at high altitude

[HUGO E. CONTRERAS]

Dear Friends:

I purchased an automatic BMW 318ti in Washington, on September 1995. Actually the car has 27,800 miles (it´s not a mistake) and, after four years in America and four years in Lima, Peru, the car is in La Paz, Bolivia, one of the highest cities in the world (above 3,800 meters above level of seas, around 11,000 feet).

When car arrived here (a truck transported my car from Lima to La Paz), I faced some troubles to start on the engine, when I got it, after brief minutes a light appeared on the dashboard ("check engine"), but the light dissapeared when the tachometer goes up 2000 rpm and above.

After one hour and minutes of running, the temperature of the engine began to go down and finally seemed to be stable.

Technicians discovered problems with thermostat and they replaced it, but car had problems to start on the engine every morning. Just one week before car arrived here, I replaced the battery (a German made Bosch, suitable for the model).

When the car was in Washington and, in Lima, Peru, the car was in excellent conditions and performance was excellent.

I will apreciate your suggestions. The altitude could affect the performance of the car?

[Travis]

Hugo:

I can only guess that the engine management sensor has'nt the foggiest idea what to do with the air at 28,000 feet. If there happens to be a BMW dealer in town, ask them if there is a high altitude version of the emgine management software.

For a better answer, sign up for the 318ti group at yahoo.com (there are som really bright guys over there, including at least one engine management software programmer).

-Travis

[HUGO E. CONTRERAS]

MY DEAR FRIEND,

THANKS A LOT FOR YOUR SUGGESTIONS AND ADVICES. ACTUALLY, THREE OTHER COMPACTS ARE CIRCULATING IN THIS CITY AND AN ENTERPRISE ("ELITE MOTORS"), ARE SELLING AND GIVING TECHNICAL SUPPORT FOR BIMMERS IN THIS COUNTRY.

MY MOTOR SERVICE DID SOME MODIFICATIONS TO COMPUTER AND TO O2 SENSOR. RIGHT NOW CAR IS STARTING ON IN A SMOOTH WAY.

BEST REGARDS,

HUGO

[tastade]

The car probably just has to relearn new fuel mixtures. At 11,000 feet the air is about 33% less dense(assuming standard of 3%/1,000 feet), so you will loose about 1/3 of your horsepower.

Because of this less dense air, it may be harder for the car to keep the air fuel mixture correct, especially during a cold start. One thing you may try is holding the accelerator down approximately 1/2 way while you start the car, this might help it start better. Many owners manuals say to do this for high elevation, I know honda does anyway.

I used to live in Laramie, WY, US where the elevation was 7,000 feet. Sometimes on cold mornings the car would have a little difficulty starting, I would just tap the gas and it would start right up.

At that elevation, a supercharger would be very helpful. The car would probably run better because it would restore the air/fuel ratio closer to what it would be at sea level.

As for the check engine light, that just means a sensor is reading out of the range it is supposed to. That could possibly be caused by the high elevation causing a sensor to look like it has failed, when it is really just the elevation making the sensor report a value that the computer thinks is wrong.

[HUGO E. CONTRERAS]

THANKS A LOT FOR YOUR ADVICES.

ONE MORE QUESTION: TECHNICIANS ADVISED ME TO USE SOME GAS BOOSTERS TO INCREASE GASOLINE POWER. HERE IN LA PAZ MANY BMWs ARE HAPPILY RUNNING, MOST OF THEM ARE E36 MODELS.

HERE YOU CAN GET ONLY TWO TYPES OF GASOLINE: SO CALLED "ESPECIAL" (SPECIAL, NO MORE THAN 81 OCTANES, UNLEADED) AND SO CALLED "PREMIUM" (NO MORE THAN 88 OCTANES, UNLEADED).

BECAUSE ALTITUDE, THESE TYPES OF GASOLINE GAVE BETTER PERFORMANCE.

CONSIDERING ALTITUDE, GAS BOOSTERS COULD BE GOOD FOR MY CAR?

BEST REGARDS,